<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <link rel="stylesheet" href="style.css">
    <title>Document</title>
</head>

<body>
    
    <div class="container">
        <button>Нажать</button>
        <div class="outer">
            <button>Нажать</button>
            <div class="inner">
                <button>Нажать</button>
            </div>
        </div>
    </div>

</body>

<script src="script.js"></script>

</html>